Manual valve control for multi-speed planetary transmission

ABSTRACT

A manual valve control for a multi-speed vehicle transmission is provided. Electronic and hydraulic components are provided, including trim valve systems that are multiplexed by a shift valve and a manual valve. The trim valves and shift valve are self-diagnosing via a plurality of multiplexed pressure switches. The control enables single and double range shifts among the multiple forward speed ratios, including shifts to and from sixth and higher forward ratios, reverse and neutral. The control also includes a reduced engine load at stop feature. In addition, a power off/limp home feature provides a plurality of failure modes, including a failure mode for sixth and higher forward speed ratios.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/023,829, filed Feb. 9, 2011, U.S. Pat. No. 8,070,637, patent issuedate is Dec. 6, 2011, which is a continuation of U.S. patent applicationSer. No. 12/170,566, filed Jul. 10, 2008, now U.S. Pat. No. 7,896,769,patent issue date is Mar. 1, 2011, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/045,141, filed Apr. 15, 2008,all of which are incorporated herein by this reference in theirentirety.

BACKGROUND

Many types of multi-speed transmissions are available for motorvehicles. One such type is a six-speed planetary transmission havingclutch-to-clutch shifting controls, as disclosed by Polak in U.S. Pat.No. 4,070,927. A higher number of forward speed ratios may be desirableto increase the operating range of the vehicle engine, improve shiftquality, improve fuel economy, or for other reasons. For example, seven-and eight-speed automatic transmissions have now been developed. Anumber of potential challenges to commercial availability ofhigher-order transmissions exist; however, including increased size,complexity and cost of such transmissions.

The clutches or other shift mechanisms of automatic transmissions aretypically controlled by electro-hydraulic systems in which electroniccontrols selectively actuate hydraulic valves, which control thedistribution of pressurized fluid to engage and disengage the shiftmechanisms upon command. Examples of prior electro-hydraulic controlsystems are disclosed in U.S. Pat. Nos. 4,827,806; 5,601,506; 5,616,093;6,520,881; and 7,140,993, all of which are issued to Long et al.

SUMMARY

According to one aspect of the present invention, a manual valve controlfor a vehicle transmission having more than six forward speeds isprovided. The manual valve control includes a plurality ofelectro-hydraulic trim valve systems configured to receive electricalsignals and selectively communicate pressurized fluid to a number oftransmission shift mechanisms, wherein the number of transmission shiftmechanisms is greater than the number of electro-hydraulic trim valvesystems, a shift valve in selective fluid communication with at leastone of the trim valve systems and with at least one of the transmissionshift mechanisms, and a manual valve having a plurality of manuallyselectable positions.

The control may include first, second, third and fourth trim valves anda plurality of passages configured to selectively fluidly couple thefirst, second, third, and fourth trim valves, the shift valve, and themanual valve to first, second, third, fourth and fifth transmissionshift mechanisms. The first and second trim valves, the shift valve andthe manual valve may control the first, second and third transmissionshift mechanisms, and the third and fourth trim valves may control thefourth and fifth transmission shift mechanisms.

The control may include an electronic control and first, second, third,fourth, and fifth actuators actuatable by the electronic control,wherein the first, second, third and fourth actuators selectivelyprovide output pressure to the first, second, third and fourth trimvalves, respectively, and the fifth actuator selectively provides outputpressure to the shift valve. The first and second actuators may benormally high solenoids. The fifth actuator may be a normally low,on/off solenoid. The sixth actuator may be actuatable to provide outputpressure to a torque converter flow valve to selectively controlapplication of a torque converter clutch.

The control may include a reduced engine load at stop subsystem operablycoupled to the torque converter flow valve. The reduced engine load atstop subsystem may selectively disengage a torque converter pump clutchfrom a drive unit of the vehicle.

The control may include a boost valve in fluid communication with atleast one trim valve system and the shift valve.

According to another aspect of the present invention, a manual valvecontrol for an automatic transmission of a vehicle is provided. Thecontrol includes at least one trim valve system configured toselectively distribute fluid pressure to at least one transmission shiftmechanism, a shift valve operable to selectively distribute fluidpressure to a first transmission shift mechanism, a manual valveoperable to selectively distribute fluid pressure to second and thirdtransmission shift mechanisms, an actuator configured to selectivelyreceive electrical signals from a controller and selectively cause fluidpressure to be applied to the shift valve, and a plurality of passagesselectively fluidly coupling the manual valve and the shift valve, atleast one of the passages being configured to selectively communicatemain pressure between the shift valve and the manual valve.

In connection with a transmission including reverse, neutral, and firstthrough eighth forward ranges, the passages may be configured such thatin the event of a power failure, the neutral range maintains the neutralrange, the reverse range maintains the reverse range, the first, second,third and fourth forward ranges fail to the third forward range, and thefifth, sixth, seventh and eighth forward ranges fail to the sixthforward range.

The control may include a valve-to-valve passage selectively fluidlycoupling the shift valve to a trim valve system and a check valvedisposed in the valve-to-valve passage to selectively communicate fluidpressure to the shift valve.

Where the transmission includes a reverse range, a neutral range, and aplurality of forward ranges, the control may include at least two trimvalve systems, and the passages selectively fluidly coupling the shiftvalve and the manual valve to each other may be configured such thatwhen the vehicle is in the neutral range, only one trim valve system isactivated.

In connection with a transmission including a reverse range, a neutralrange, and first through eighth forward ranges, the passages selectivelyfluidly coupling the shift valve and the manual valve to each other maybe configured such that the shift valve distributes fluid pressure tothe first transmission shift mechanism when the vehicle is in the first,second, or third forward range, the manual valve distributes fluidpressure to the second transmission shift mechanism when the vehicle isin the fourth, fifth, or sixth forward range, and the manual valvedistributes fluid pressure to the third transmission shift mechanismwhen the vehicle is in the sixth, seventh or eighth forward range.

According to another aspect of the present invention, a manual valvecontrol for an automatic transmission of a vehicle is provided. Thecontrol includes a plurality of trim valves, a shift valve in selectivefluid communication with at least one of the trim valves and with aplurality of transmission shift mechanisms, and a plurality of pressureswitches operably coupled to the trim valves and the shift valve todetect the position of each of the trim valves and the shift valve,wherein the number of pressure switches is less than the sum of thenumber of trim valves plus the shift valve.

The control may include first, second, third and fourth trim valves, andfirst, second, third and fourth pressure switches in fluid communicationwith the first, second, third and fourth trim valves, respectively, andat least one of the pressure switches may detect the position of a trimvalve and also be configured to detect the position of the shift valve.The pressure switches may be operable to detect changes in the positionsof the trim valves and the shift valve corresponding to single rangeshifts, double range shifts, and reverse directions. A valve to valvepassage selectively fluidly coupling two of the pressure switches to apressurized fluid passage. The control may include a manual valve havinga plurality of manually selectable positions, and two of the pressureswitches may be configured to detect a position of the manual valve.

Patentable subject matter may include one or more features orcombinations of features shown or described anywhere in this disclosureincluding the written description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description refers to the following figures in which:

FIG. 1 is a simplified block diagram of a motor vehicle powertrainincluding an electro-hydraulic control system for a multi-speedtransmission of a motor vehicle in accordance with the presentinvention;

FIG. 2 is a schematic diagram of one embodiment of a control system fora multi-speed transmission for a motor vehicle, showing a fluid passagearrangement and fluid pressure configuration for a reverse mode ofoperation of the motor vehicle;

FIG. 3 is a schematic diagram of the embodiment of FIG. 2, showing afluid passage arrangement and fluid pressure configuration for a neutralmode of operation of the motor vehicle;

FIGS. 4-13 are schematic diagrams of the embodiment of FIG. 2, showingfluid passage arrangements and fluid pressure configurations for variousoperational ranges of a motor vehicle, including first through eighthforward speed ratios;

FIG. 14 is a schematic diagram of the embodiment of FIG. 2, showing afluid passage arrangement and fluid pressure configuration for a reversemode of operation of the motor vehicle when no electrical power isprovided to the control system;

FIG. 15 is a schematic diagram of the embodiment of FIG. 2, showing afluid passage arrangement and fluid pressure configuration for a neutralmode of operation of the motor vehicle when no electrical power isprovided to the control system;

FIG. 16 is a schematic diagram of the embodiment of FIG. 2, showing afluid passage arrangement and fluid pressure configuration for a thirdforward ratio of the motor vehicle when no electrical power is providedto the control system;

FIG. 17 is a schematic diagram of the embodiment of FIG. 2, showing afluid passage arrangement and fluid pressure configuration for a sixthforward ratio of the motor vehicle when no electrical power is providedto the control system; and

FIG. 18 is a legend indicative of fluid pressures shown in FIGS. 2-17.

In general, like structural elements on different figures refer toidentical or functionally similar structural elements, althoughreference numbers may be omitted from certain views of the drawings forease of illustration.

DETAILED DESCRIPTION

Aspects of the present invention are described with reference to certainillustrative embodiments shown in the accompanying drawings anddescribed herein. While the present invention is described withreference to the illustrative embodiments, it should be understood thatthe present invention as claimed is not limited to the disclosedembodiments.

FIG. 1 depicts a simplified logical block diagram of anelectro-hydraulic transmission control 16 in the context of an exemplaryvehicle powertrain 10. Control 16 comprises an electro-hydraulicapparatus that is capable of providing full control of an eight speedplanetary transmission. Control 16 controls single range shifts, doublerange (or “skip”) shifts, “garage” shifts, application and release of atorque converter clutch, and provides a reduced engine load at stop(RELS) feature, and also provides power failure/limp-home protection inmultiple ranges, as described herein. Garage shifts are shifts fromneutral to a forward ratio, from neutral to reverse, or between forwardand reverse. Limp-home refers to the capability of the transmissioncontrol to automatically cause the transmission to assume a predefinedoperating range in the event of a transmission power failure, so thatthe vehicle can be safely operated or taken out of operation once thefailure is detected.

Control 16 includes a shift valve and a plurality of trim valve systems,such that the number of trim systems required to operate thetransmission 18 is less than the number of clutches or other shiftmechanisms provided by the transmission, while still providing all ofthe features mentioned above. Trim systems can be costly; therefore, areduction in the number of required trim systems may be consideredadvantageous, particularly as the number of shift mechanisms in thetransmission increases.

In FIG. 1, the lines shown as connecting blocks 12, 14, 16, 18, 20, 22,24, 26, 28 of powertrain 10 represent logical connections which, inpractice, may include one or more electrical, mechanical and/or fluidconnections, passages, couplings or linkages, as will be understood bythose skilled in the art and as described herein.

Powertrain 10 includes drive unit 12, torque transferring apparatus 14,electro-hydraulic transmission control 16, multi-speed transmission 18and final drive 20. Drive unit 12 generally provides a torque output totorque transferring apparatus 14. Drive unit 12 may be an internalcombustion engine of a compression-ignition type (i.e. diesel) or aspark-ignition type (i.e. gasoline), or the like. Torque transferringapparatus 14 selectively establishes a coupling between drive unit 12and transmission 18 to convert and/or transfer the torque output fromdrive unit 12 to the vehicle transmission 18. As such, torquetransferring apparatus 14 normally includes a fluid coupling such as atorque converter.

Transmission 18 includes an input shaft, an output shaft, an assembly ofgears, and a plurality of gear-shifting mechanisms that are selectivelyengaged and disengaged by electro-hydraulic transmission control 16 tocause the vehicle to assume one of a plurality of operational modes orranges including at least eight forward speed ratios, neutral, andreverse. As such, the shift mechanisms of transmission 18 are in fluidcommunication with hydraulic control elements of control 16.

The embodiment of control 16 shown in FIGS. 2-17 relates to aneight-speed transmission that includes four planetary gearsets and fiveshift mechanisms (C1, C2, C3, C4, C5), which are configured so that twoshift mechanisms are applied in any range (except neutral). A chartshowing an example of numerical values for gear ratios and ratio stepscorresponding to the various gear states of an eight speed transmissionhaving four planetary gearsets and five shifting mechanisms is providedin Long et al., U.S. Provisional Patent Application Ser. No. 61/045,141,filed Apr. 15, 2008, which is incorporated herein by this reference.Those of ordinary skill in the art will understand that suchtransmission is offered only as an example, and that aspects of thepresent invention are applicable to other multi-speed transmissions.

In this disclosure, the term “shift mechanism” may be used to refer toone or more clutches, brakes, or other friction elements or devices, orsimilar suitable mechanisms configured to cause the transmission toswitch from one range or gear ratio to another, different range or gearratio.

Transmission 18 drives the vehicle load 20. Vehicle load 20 generallyincludes the drive wheels and driven load mass. The actual weight ofvehicle load 20 may be quite considerable and/or vary considerably overthe course of the vehicle's use, as may be the case with commercialvehicles such as trucks, buses, emergency vehicles, and the like.

Torque transferring apparatus 14 may include one or more selectivelyengageable and disengageable couplers such as a torque converter clutch26 and/or a pump clutch 28, which may be configured to alter thecoupling between drive unit 12 and transmission 18. Torque converterclutches (also known as “lockup” clutches) are often provided to effectunitary rotation of the torque converter pump and turbine in response toreduced hydraulic pressure within the torque converter, which may occurwhen “slip” (i.e., a difference in rotational speed) between the torqueconverter pump and turbine is not required. A pump clutch may beselectively disengaged to effect a decoupling of the torque converterpump from the drive unit to reduce the engine load; i.e., when thevehicle is idling, decelerating, or operating at lower speed ratios, forexample. Reducing engine load in this manner may improve fuel efficiencyof the vehicle and/or provide other advantages.

Couplers 26, 28 of torque transferring apparatus 14 and shift mechanismsC1, C2, C3, C4, C5 are each configured to selectively achieve amechanical, fluid or friction coupling between components of thepowertrain 10 in response to various conditions or changes inconditions. For instance, one or more of couplers 26, 28 and shiftmechanisms C1, C2, C3, C4, C5 may be torque transmitting devices orfriction devices. One or more of couplers 26, 28 and shift mechanismsC1, C2, C3, C4, C5 may be fluid-operated devices such as clutch- orbrake-type devices. As such, one or more of couplers 26, 28 and shiftmechanisms C1, C2, C3, C4, C5 may be stationary- or rotating-typedevices.

In general, each of couplers 26, 28 and shift mechanisms C1, C2, C3, C4,C5 can be operated independently of each other. For instance, anycombination of couplers 26, 28 and shift mechanisms C1, C2, C3, C4, C5may be engaged and disengaged at a given time. Such devices 26, 28, C1,C2, C3, C4, and C5 may be referred to individually or collectivelyherein as “torque transmitting mechanisms.”

Electrical control 22 controls operation of transmission 18 based oninputs from one or more components of drive unit 12, torque converter14, transmission 18, range selector 24; and/or other inputs. Such inputsmay include electrical and/or analog signals received from sensors,controls or other like devices associated with the vehicle components.For instance, inputs may include signals indicative of transmissioninput speed, driver requested torque, engine output torque, enginespeed, temperature of the hydraulic fluid, transmission output speed,turbine speed, brake position, gear ratio, torque converter slip, and/orother measurable parameters.

Electrical control 22 generally includes electrical circuitry configuredto process, analyze or evaluate one or more inputs and issue electricalcontrol signals to electro-hydraulic control system 16, as needed,through one or more electrical lines, conductors, or other suitableconnections. Such connections may include hard-wired and/or networkedcomponents in any suitable configuration including, for example,insulated wiring and/or wireless transmission as may be appropriate ordesired.

Electrical circuitry of control 22 includes computer circuitry such asone or more microprocessors, integrated circuits and related elementsconfigured to process executable instructions expressed in computerprogramming code or logic, which is stored in one or more tangiblemedia, i.e., any suitable form of memory or storage media that isaccessible or readable by the processor or processors. Control 22 mayalso include analog to digital converters and/or other signal processingcircuitry or devices as needed to process one or more of the inputsreceived from the vehicle components.

While shown schematically in FIG. 1 as a single block 22, it will beunderstood by those skilled in the art that portions of control 22 maybe implemented as separate logical or physical structures. For example,electronic controls for transmission 18 may be physically and/orlogically separated from electronic controls for drive unit 12.

Manual range selector 24 interfaces with an operator of the vehicle andconverts the operator's manually-driven requests into signals orcommands indicative of a selected or desired operational mode of thevehicle, i.e., park, drive, reverse, or neutral. In the illustratedembodiment, range selector 24 is a “manual valve” range selectingmechanism, rather than a fly-by-wire control. Manual valve selectorsrequire at least some range shift selections to be mechanicallyactuated, for example, park-to-neutral, neutral-to-reverse, andneutral-to-drive. The structure and operation of an exemplary manualvalve MV1 is shown in FIGS. 2-17 and described below.

As shown in FIGS. 2-17, control 16 comprises manual valve MV1, a shiftvalve SV1, and a plurality of trim systems PCS2, PCS5, PCS3, PCS4,wherein the number of trim systems is less than the number of shiftmechanisms being controlled thereby. Additionally, control 16 comprisesa source of pressurized hydraulic fluid 72, 74, a main or line regulatorvalve 76, a control or actuator feed regulator valve 70, a torqueconverter flow regulator valve 78, a RELS valve 68, a plurality ofpressure regulator or trim valves 60, 62, 64, 66 (each trim valve beingpart of a trim system), a boost valve 80, a plurality of EBF valves 82,84, a plurality of check valves 88, 90, 92, 94, a lube regulator valve86, a plurality of hydraulic accumulators 50, 52, 54, 56, a plurality oforifices or restrictors 116, 118, 120, 122, 124, 126, 128, 130, 132,134, 136, 138, 140, 142, 144, 146, 148, 150, 152, 154, 156, 158, 160,161, 162, a plurality of pressure switches PS2, PS3, PS4, PS5, aplurality of electrical actuators 30, 32, 34, 36, 38, 40, 42, and 46,and a plurality of interconnecting fluid passages including a mainpassage 100, a control passage 102, a converter feed passage 104, a pumpreturn passage 106, a plurality of valve feed passages 114, 170, 172,174, 176, 178, 180, 182, a plurality of valve-to-shift mechanismpassages 190, 192, 194, 196, 198, 200, and a plurality of valve-to-valveor intermediate or inter-valve passages including passages 210, 212,214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 236, 342, 344,346. FIG. 18 provides a legend indicating the various fluid pressuresdepicted in FIGS. 2-17.

In general, each of main regulator valve 76, actuator feed regulatorvalve 70, torque converter flow regulator valve 78, RELS valve 68, trimvalves 60, 62, 64, 66, shift valve SV1, boost valve 80, and luberegulator valve 86 includes a valve head, a valve spool, at least onevalve land interposed between portions of the valve spool or between thevalve head and a portion of the valve spool, and a return springdisposed in a spring chamber. Each valve spool is axially translatablein a valve bore in response to changes in fluid pressure or fluid flowthrough the various passages of control 16. For ease of illustration,the valve bores have been omitted from the figures.

The valve lands each define a diameter that is greater than the diameterdefined by the valve spool, such that surfaces of the lands may slidablyengage interior surfaces of the valve bore when the valve spooltranslates within the valve bore. Spool portions between valve lands mayselectively connect fluid passages to other fluid passages, or connectfluid passages to fluid chambers, depending on the position of thevalve.

Each return spring biases its respective valve in a first or spring setposition. Changes in fluid pressure or fluid flow in selected fluidpassages may cause the valve spool to translate within the valve bore,causing the return spring to partially or fully compress. Shift valveSV1 is slidable between the first or spring set position and a second orstroked or pressure set position, where the second or stroked orpressure set position is one in which the return spring is fullycompressed. Others of the valves, such as trim valves 60, 62, 64, 66,are configured to assume intermediate positions between the first andsecond positions, in which the return spring is partially compressed, inaddition to the first and second positions.

Manual valve MV1 has a plurality of selectable, discrete positions. Inthe illustrated embodiment, manual valve MV1 has at least three manuallyselectable positions: reverse, neutral, and drive.

In general, the restrictors or orifices 116, 118, 120, 122, 124, 126,128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148, 150, 152, 154,156, 158, 160, 161, 162 are positioned in various fluid passages toalter or moderate the rate of fluid flow through the passages or aportion thereof, in order to control the rate at which pressure in afluid passage changes. Such restrictors are used to provide additionalcontrol over fluid pressure in the passages, or for other reasons.

Actuators 30, 32, 34, 36, 38, 40, 42, and 46 are operably coupled tocontrol 22 to receive electrical signals (i.e. current) therefrom andselectively actuate valves 60, 62, 64, 66, 68, 70, 76, 78, SV1, toattain, maintain, or transition between the various operational modes oftransmission 18. In general, each of actuators 30, 32, 34, 36, 38, 40,42, 46 may be a solenoid valve of either the on/off or variable bleedtype. In the illustrated embodiment, actuator 42 is an on/off solenoid,while actuators 30, 32, 34, 36, 38, 40, and 46 are of the variable bleedtype.

Additionally, each of actuators 30, 32, 34, 36, 38, 40, 42, 46 is eitherof the normally low type or of the normally high type. A normally low(or normally off) solenoid valve provides maximum output pressure whenit receives electrical input and provides zero or minimum outputpressure when no electrical input is received; while a normally high (ornormally on) solenoid valve provides maximum output pressure when it isnot receiving any electrical input and provides zero or minimum outputpressure when electrical input is provided. Thus, as used herein, whenreferring to an actuator or solenoid valve as being “actuated,” thismeans either that electrical input is supplied to the solenoid (as inthe case of normally low solenoids) or that electrical input is notsupplied to the solenoid (as in the case of normally high solenoids). Inthe illustrated embodiment, actuators 30, 32, and 46 are normally highsolenoids while actuators 34, 36, 38, 40, 42, are normally lowsolenoids.

In general, pressure switches PS2, PS3, PS4, PS5, are each configured toissue an electrical output signal to control 22 when a predeterminedfluid pressure is detected by the switch, for diagnostic purposes or forother reasons. Such electrical signals inform control 22 of changes instatus of components of control 16. In the illustrated embodiment, thenumber of pressure switches in control 16 is less than the number offorward ratios provided by transmission 18. Also, the number of pressureswitches is less than the sum of the number of trim systems plus theshift valve SV1. The number of pressure switches is also less than thenumber of shift mechanisms (i.e., C1, C2, C3, C4, C5) in transmission18.

In the illustrated embodiment, pressure switches PS2, PS5, PS3, PS4 arein fluid communication with trim valves 60, 62, 64, 66, respectively.Pressure switches PS2, PS5, PS3, PS4 thereby detect changes in fluidpressure that are indicative of changes in position of trim valves 60,62, 64, 66, respectively. Pressure switches PS2, PS5, PS3, PS4 areactivated when the corresponding trim valve 60, 62, 64, 66 is actuatedby control pressure, as shown in the figures.

Pressure switches PS2, PS3, PS4, PS5, which correspond to the trimsystems PCS2, PCS3, PCS4, PCS5 are activated by the trim pressure, asshown in Table 2 and Table 3, or by the control or main pressure, asshown in Table 1. An example of a pressure switch that is activatedwhenever its associated valve is in either a “trim” state or an “on”state is disclosed in Long et al., U.S. Pat. No. 6,382,248.

Actuators 30, 32, 34, 36, 38, 40, 42, 46, and pressure switches PS2,PS3, PS4, PS5, are in electrical or electronic communication withcontrol 22 by suitable electrical wiring, electric networks, and/orwireless channels, as will be understood by those skilled in the art.However, for ease of illustration, logical representations of many ofthese electrical connections have been omitted from FIGS. 2-17.

During operation of the vehicle, pump 72 draws hydraulic fluid fromfluid supply, sump or reservoir 74 and supplies it to main regulatorvalve 76. Main regulator valve 76 distributes the fluid to main passage100 at a main or “line” pressure. In general, the main pressure definesa range including a minimum system pressure and a maximum systempressure for main passage 100. In the illustrated embodiment, the mainpressure is in the range of about 50-250 pounds per square inch (psi).

Main regulator valve 76 distributes fluid at the main pressure toactuator feed regulator valve 70, RELS valve 68, converter flow valve78, trim valves 60, 62, and manual valve MV1, directly via main passage100.

Main regulator valve 76 is in fluid communication with main modulatoractuator 46 via passage 114. Actuator 46 is also in fluid communicationwith control passage 102. Actuator 46 is actuated by electronic orelectrical control 22 to modulate or control the fluid pressure level inmain passage 100 via main regulator valve 76.

Control 22 selectively provides signals to actuator 46 based on engineoutput torque, throttle position, or other parameters or factors. Ingeneral, the output pressure of actuator 46 in passage 114 is variableand less than the main pressure. In the illustrated embodiment, actuator46 is a normally high solenoid valve with an output pressure in passage114 varying in the range of about 0-110 psi.

When fluid pressure in main passage 100 is satisfied, main regulatorvalve 76 distributes fluid pressure to converter feed passage 104, whichis in fluid communication with converter flow valve 78, relief valve 98and lube regulator valve 86. Converter flow valve 78 distributes fluidin passage 104 to fluid chamber 108 of torque converter 14.

Converter flow valve 78 and/or relief valve 98 distributes fluid frompassage 104 to cooler system 110. In general, cooler system 110 isoperable to maintain the temperature of the hydraulic fluid within asuitable temperature range. In the illustrated embodiment, the operatingtemperature of the hydraulic fluid is in the range of about −40° C. toabout +120° C.

Lube regulator valve 86 distributes fluid from passage 104 and/or cooler110 to lubrication system fluid chamber 112. Lube system fluid chamber112 provides fluid to lubricate various components of the transmission18, such as components of the planetary gear sets including gears andbearings.

Relief valve 98 prevents overpressure of converter 14, during a coldstartup, for example. After the fluid requirements of torque converterfluid chamber 108, lube system fluid chamber 112 and cooler system fluidchamber 110 are met, any remaining fluid may be returned to a pumpreturn passage 106. During “normal” operation in which pump 72 isdrawing fluid from reservoir 74, fluid in pump return passage 106 is ata negative pressure. In the illustrated embodiment, the negativepressure is in the range of about −2 psi.

The fluid pressure in converter feed passage 104, which may be referredto as the “converter” pressure, is generally less than the mainpressure. In the illustrated embodiment, the converter pressure is inthe range of about 100 psi.

Actuator feed regulator valve 70 and actuator 46 are in direct fluidcommunication with, and thereby maintain fluid at a “control” pressure,in control passage 102. Control passage 102 is in direct fluidcommunication with, and thereby supplies control pressure to, actuators30, 32, 34, 36, 38, 40, 42, 44, and 46, boost valve 80, and check valves88, 90, 92. The control pressure is generally less than the mainpressure and greater than the converter pressure. In the illustratedembodiment, the control pressure is in the range of about 110 psi.

A torque converter clutch control subsystem, TCC, includes actuator 40,fluid passage 180, and torque converter flow valve 78. The TCC subsystemcontrols engagement and disengagement of the torque converter clutch or“lockup” clutch 26. To apply the torque converter clutch 26, pressure inthe torque converter fluid chamber 108 is reduced. The pressure inchamber 108 is reduced by actuating actuator 40 to provide controlpressure in passage 180, thereby applying control pressure to valve head186 of converter flow valve 78, causing valve 78 to move to the pressureset position shown in FIGS. 7-13. When valve 78 is in the pressure setposition, land 188 opens converter fluid chamber 108 to exhaust to applythe clutch 26. As shown by Table 1, in the illustrated embodiment, thetorque converter clutch 26 is applied in the 3^(rd) through 8^(th)forward ratios and released in the reverse, neutral, first and secondranges of the transmission 18. However, since the torque converterclutch 26 is controlled independently of the other clutches, it may beapplied or released at any time, including during neutral and reverse.For example, torque converter clutch 26 may be applied for powertake-off (PTO) applications.

In the illustrated embodiment, actuator 40 is a normally low solenoid.As such, when actuator 40 is not actuated, control 22 provides little orno electrical input to actuator 40, and the output pressure of actuator40 is zero or nearly zero psi. To actuate actuator 40, control 22supplies electrical input to actuator 40, and the output pressure ofactuator 40 is at or near the control pressure.

A reduced engine load at stop subsystem (RELS) includes actuator 38,RELS valve 68, passage 210, and torque converter flow valve 78. Ingeneral, a reduced engine load at stop system is a control that enablesan additional mechanical disconnection between the drive unit 12 and thetorque converter 14 to achieve greater engine efficiency when it isdesired to slow, stop or idle the vehicle. When the RELS system isactivated the additional disconnection is provided by mechanicallydecoupling the drive unit 12 from the torque converter pump (in additionto the mechanically decoupling of the pump from the turbine, which isaccomplished by release of the torque converter clutch 26). In theillustrated embodiment, the RELS feature is provided by disengaging thepump clutch 28 of the torque converter 14 while the torque converterclutch 26 is also disengaged. Additional description of a control for atorque converter having both a torque converter clutch and a pump clutchmay be found in Long et. al., U.S. Provisional Patent Application Ser.No. 61/045,141, filed Apr. 15, 2008, which is incorporated herein bythis reference. An example of a reduced engine load at stop control maybe found in U.S. Pat. No. 7,338,407 to Long et al., issued Mar. 4, 2008.In general, RELS valve 68 is multiplexed via actuators 38, 40 to controlboth the torque converter clutch 26 and pump clutch 28.

An example of an activation of the RELS feature in the first forwardratio is shown in FIG. 5. Torque converter clutch 26 is disengaged, asconverter flow valve 78 is in the spring set position and converterfluid chamber 108 is at the converter pressure. To activate the RELSfeature, actuator 38 is actuated, providing control pressure in passage178, which is applied to the valve head 204 as shown in FIG. 5. Strokingthe RELS valve 68 causes land 206 to open passage 210 to connect withmain passage 100, thereby providing main pressure to RELS fluid chamber202. The pressure increase in RELS fluid chamber 202 causes pump clutch28 to disengage.

In the illustrated embodiment, actuator 38 is a normally low solenoid.As such, when actuator 38 is not actuated, control 22 provides little orno electrical input to actuator 38, and the output pressure of actuator38 is zero or nearly zero psi. To actuate actuator 38, control 22supplies electrical input to actuator 38. When actuated, the outputpressure of actuator 38 is at or near the control pressure.

The shift mechanisms, i.e., C1, C2, C3, C4, C5 of transmission 18 arecontrolled by trim systems PCS2, PCS5, PCS3, and PCS4. Each of the trimsystems PCS2, PCS5, PCS3, and PCS4 includes an actuator 30, 32, 34, 36,a trim valve 60, 62, 64, 66, a trim valve feed passage 170, 172, 174,176, a restrictor 122, 124, 120, 118 disposed in passages 170, 172, 174,176, an accumulator 50, 52, 54, 56, and a pressure switch PS2, PS5, PS3,PS4.

Trim system PCS2 includes actuator 30, accumulator 50, trim valve 60,feed passage 170, restrictor 122, pressure switch PS2, valve-to-shiftmechanism passage 218, which is in fluid communication with shiftmechanism fluid chamber C2 via manual valve MV1. Restrictors 134, 156are disposed in passage 218, with restrictor 134 being disposed nearerto trim valve 60 and restrictor 156 being disposed nearer to the inletto fluid chamber C2.

In the illustrated embodiment, actuator 30 is a normally high solenoidvalve. As such, when control 22 provides little or no electrical inputto actuator 30, the output pressure of actuator 30 in passage 170 is ator near the control pressure. When control 22 supplies electrical inputto actuator 30, the output pressure of actuator 30 is zero or nearlyzero psi.

Trim system PCS5 includes actuator 32, accumulator 52, trim valve 62,feed passage 172, restrictors 124, 136, 148, pressure switch PS5, valveto valve passage 220, which is in fluid communication with boost valve80, and valve to valve passage 222, which is in fluid communication withshift valve SV1.

In the illustrated embodiment, actuator 32 is a normally high solenoidvalve. As such, when control 22 provides little or no electrical inputto actuator 32, the output pressure of actuator 32 in passage 172 is ator near the control pressure. When control 22 supplies electrical inputto actuator 32, the output pressure of actuator 32 is zero or nearlyzero psi.

Boost valve 80 is in fluid communication with fluid chamber C5 b viavalve to shift mechanism passage 200. Restrictor 138 is disposed inpassage 200 near the inlet to fluid chamber C5 b. In general, boostvalve 80 is actuated whenever trim valve 62 reaches a predeterminedlevel (which may be set by adjusting the return spring on boost valve80). The predetermined level is set to ensure that the clutch C5 isfully applied. In the illustrated embodiment, the predetermined level oftrim valve 62 for actuating boost valve 80 is in the range of about 50to about 60 psi. As boost valve 80 is in fluid communication with bothchamber C5 a and C5 b, boost valve 80 is configured as a dual areaactivation valve similar to one disclosed in Ellis et al., U.S. patentapplication Ser. No. 11/856,751, filed Sep. 17, 2007 (Attorney DocketNo. P001573).

Shift valve SV1 is in fluid communication with fluid chamber C5 a viavalve to shift mechanism passage 198. Restrictor 162 is disposed inpassage 198 near the inlet to fluid chamber C5 a. Shift valve SV1 isalso in fluid communication with fluid chamber C5 b via passage 198 andboost valve 80. Actuator 42 is operably coupled to shift valve SV1. Inthe illustrated embodiment, actuator 42 is a normally low solenoid. Assuch, when actuator 42 is not actuated, control 22 provides little or noelectrical input to actuator 42, and the output pressure of actuator 42is zero or nearly zero psi. To actuate actuator 42, control 22 supplieselectrical input to actuator 42. When actuated, the output pressure ofactuator 42 to valve head 250 is at or near the control pressure.

Manual valve MV1 is in fluid communication with shift mechanism fluidchamber C1 via valve to shift mechanism passage 190. Restrictor 158 isdisposed in passage 190 near the inlet to fluid chamber C1. Manual valveMV1 is also in fluid communication with shift mechanism fluid chamber C2via passage 192. Restrictor 156 is disposed in passage 192 near theinlet to fluid chamber C2. The position of manual valve MV1 is changedby the vehicle operator.

Shift valve SV1 and manual valve MV1 are in fluid communication witheach other via a plurality of valve to valve passages 224, 226, 228.Check valve 94 is disposed in passage 236, which connects shift valveSV1 to trim system PCS5. In this way, trim systems PCS2 and PCS5 aremultiplexed via shift valves SV1 and manual valve MV1 to selectivelycontrol the engagement and disengagement (or application and release) ofshift mechanisms C1, C2, and C5.

Trim system PCS3 selectively controls engagement and disengagement ofshift mechanism C3. Trim system PCS3 includes actuator 34, accumulator54, trim valve 64, pressure switch PS3, feed passage 174, restrictor 120disposed in feed passage 174, valve to shift mechanism passage 194 andrestrictor 132 disposed in passage 194 near the inlet to shift mechanismfluid chamber C3. Actuator 34 is a normally low solenoid. As such, whencontrol 22 provides little or no electrical input to actuator 34, theoutput pressure of actuator 34 is zero or nearly zero psi. When control22 supplies electrical input to actuator 34, the output pressure ofactuator 34 in passage 174 is at or near the control pressure.

Trim system PCS4 selectively controls engagement and disengagement ofshift mechanism C4. Trim system PCS4 includes actuator 36, accumulator56, trim valve 66, pressure switch PS4, feed passage 176, restrictor 118disposed in feed passage 176, valve to shift mechanism passage 196 andrestrictor 150 disposed in passage 196 near the inlet to shift mechanismfluid chamber C4. Actuator 36 is a normally low solenoid. As such, whencontrol 22 provides little or no electrical input to actuator 36, theoutput pressure of actuator 36 is zero or nearly zero psi. When control22 supplies electrical input to actuator 36, the output pressure ofactuator 36 in passage 176 is at or near the control pressure.

In the illustrated embodiment, an accumulator 50, 52, 54, 56 is in fluidcommunication with each of the trim systems PCS2, PCS3, PCS4, PCS5. Suchaccumulators or similar devices may be used to hydraulically filter stepchanges in the output pressure of the respective actuators 30, 32, 34,36, or for other purposes. However, it will be understood by thoseskilled in the art that the inclusion of accumulators 50, 52, 54, 56 isconsidered optional.

Table 1 shows the components of control 16 that are actuated when eachof the various operational modes of transmission 18 are achieved. Table1 also shows the shift mechanism(s) and torque converter coupler(s) thatare typically activated in each mode. The asterisk is used to indicatethat what is shown is a typical configuration. However, the torqueconverter clutch can be actuated at any time.

TABLE 1 STEADY STATE MECHANIZATION Torque Shift Trim Shift PressureConverter Pump Mechanism(s) System(s) Valve Switch(s) Clutch ClutchRange Applied Actuated Actuated? Actuated Status* Status Reverse C2, C5PCS2, No PS2, PS4 Released Applied PCS5 Neutral C5 PCS5 No PS3 ReleasedApplied 1^(st) C3, C5 PCS3, No None Released Applied PCS5 RELS 1^(st)C3, C5 PCS3, No None Released Released PCS5 2^(nd) C4, C5 PCS4, No PS3,PS4 Released Applied PCS5 3^(rd) C1, C5 PCS2, No PS2, PS3 AppliedApplied PCS5 4^(th) C1, C4 PCS2, No PS2, PS3, Applied Applied PCS4 PS4,PS5 4^(th,) C1, C4 PCS2, Yes PS3, PS4 Applied Applied PCS4 5^(th,) C1,C3 PCS2, Yes None Applied Applied PCS3 6^(th,) C1, C2 PCS2, Yes PS3, PS5Applied Applied PCS5 7^(th,) C2, C3 PCS3, Yes PS2, PS5 Applied AppliedPCS5 8^(th,) C2, C4 PCS4, Yes PS2, PS3, Applied Applied PCS5 PS4, PS5

Another chart showing additional details of the steady statemechanization is provided in Long et al., U.S. Provisional PatentApplication Ser. No. 61/045,141, filed Apr. 15, 2008, which isincorporated herein by this reference. The configuration of control 16during the modes shown in Table 1 above will now be described.

Reverse

When the reverse operational mode is requested, e.g. by the vehicleoperator changing the position of range selector 24, control 16 assumesthe configuration shown in FIG. 2, in which fluid chambers C2, C5 a andC5 b are pressurized and pressure switches PS4 and PS2 detect controlpressure. Control pressure is applied to valve heads 240 and 242, byactuation of actuators 30 and 32, of trim systems PCS2, PCS5.

Actuation of actuator 30 causes downward translation of valve 60,thereby causing land 256 to move. As a result, pressure switch PS2 isconnected to control passage 102 via valve to valve passage 232, andvalve chamber 340 of shift valve SV1, thereby causing PS2 to detect thecontrol pressure. Movement of lands 256, 258 connects valve to valvepassage 218 with valve to valve passage 216. With manual valve MV1 inthe reverse position, valve to shift mechanism passage 192 is connectedto valve to valve passage 218. Passage 216 is connected to main passage100. As a result, main pressure is applied to fluid chamber C2 viarestrictor 156. Restrictor 156 and similar structures are configured toreduce the variation in the amount of time it takes to fill the clutchdue to temperature variations. In the illustrated embodiment, restrictor156 in a sharp-edged orifice.

Actuation of actuator 32 applies control pressure to valve head 242 oftrim valve 62. Downward translation of trim valve 62 causes land 262 tomove so that pressure switch PS5 is connected to exhaust passage 234,thereby causing PS5 to detect zero or nearly zero pressure. Movement oflands 262, 264 connects valve to valve passage 222 with main passage100, thereby applying main pressure to fluid chambers C5 a and C5 b viapassage 198, shift valve SV1, and restrictors 136, 138 and 162. Withvalve 62 actuated, spool portion 328 is interposed in fluid passage 220,causing control pressure to be applied to boost valve 80. As a result,lands 308, 310 move so that fluid chamber C5 b is connected with passage198. Thus, in the reverse mode, actuation of trim valves 60, 62, andboost valve 80, results in the engagement of shift mechanisms C2 and C5.

Also in the reverse mode, pressure switch PS4 is activated by controlpressure even though trim system PCS4 is not actuated by control 22.This is due to the reverse position of manual valve MV1, in which land288 blocks passage 208 to provide control pressure from passage 102 topassage 214 and pressure switch PS4.

Neutral

When the neutral operational mode is requested, e.g. by the vehicleoperator changing the position of range selector 24, control 16 assumesthe configuration shown in FIG. 3. In neutral, only one shift mechanism,C5 is actuated, via actuation of trim system PCS5 and boost valve 80 asdescribed above. None of the other trim systems PCS2, PCS3, PCS4 areactuated, and shift valve SV1 is not actuated. However, fluid chambersC5 a and C5 b remain pressurized, and pressure switch PS3 is actuated.Check valves 90, 92 retain control pressure in passage 102 and preventit from affecting the configuration of valves 60, 66.

With manual valve MV1 in the neutral position, passage 208 is connectedto exhaust. Restrictors 160 are a series of orifices that act as awasting system and prevent pressure from building in passage 208.De-activation of trim system PCS2 (relative to FIG. 2) and the resultingmovement of lands 254, 256, 258, disconnects passage 218 from passage216 and from fluid chamber C2. Due to the position of MV1, fluid chamberC2 is connected with passage 228, which is in fluid communication withEBF valves 82, 84. Fluid chamber C2 is thereby exhausted. Restrictor 156moderates the rate of exhaustion to provide smoother disengagement ofshift mechanism C2.

Movement of land 294 of manual valve MV1 increases the fluid pressure onpressure switch PS3 by blocking passage 231, which is at the controlpressure by virtue of its connection to control passage 102 viarestrictors 161. Thus, PS3 is actuated.

In general, the various forward speed ratios of transmission 18 becomeavailable when the vehicle operator places the manual valve MV1 in the“drive” position shown in FIGS. 4-13. In the illustrated embodiment,manual valve MV1 is manually translated downward relative to passage 208to achieve the drive position.

First Forward Ratio

After the vehicle operator has placed the transmission 18 in “drive”,when the first forward ratio is requested, e.g. automatically by control22 or by range selector 24, control 16 assumes the configuration shownin FIG. 4. Control pressure is applied to valve heads 242 and 244causing movement of trim valves 62, 64. Relative to the neutralconfiguration shown in FIG. 3, the configuration of trim system PCS5remains the same. However, in the first forward ratio shown by FIG. 4,main pressure is applied to engage shift mechanism C3 as a result ofactuation of actuator 34 and movement of manual valve MV1 into the driveposition. Passage 216 is in fluid communication with main passage 100and passage 230. Passage 230 is in fluid communication with valve toshift mechanism passage 194. Shift mechanism C5 remain applied due tothe connection of passages 198, 222 through shift valve SV1 due toactivation of valve 62.

None of pressure switches PS2, PS3, PS4, PS5 are activated by control ormain pressure in the first forward ratio. Relative to neutral, PS3 isdeactivated in FIG. 4 because passage 214 is in fluid communication withexhaust passage 208 (rather than passage 231, as in FIG. 3) due to theposition of lands 266, 268 and manual valve MV1. In comparison to FIG.5, which shows the RELS subsystem in an activated state; in the “normal”first forward ratio shown by FIG. 4, the RELS fluid chamber 202 is notpressurized because actuator 38 and RELS valve 68 are not actuated.

Second Forward Ratio

When the second forward ratio is requested, e.g. automatically bycontrol 22 or by range selector 24, control 16 assumes the configurationshown in FIG. 6. In the second forward ratio, the configuration of PCS2,PCS5, and shift valve SV1 remains the same as in the first forwardratio. PCS3 is not actuated, assuming the same position as in FIG. 2.Fluid chamber C3 is exhausted and pressure switch PS3 is pressurized,indicating release of shift mechanism C3. Control 22 sends electricalinput to actuator 36 to actuate PCS4. Control pressure applied to valvehead 246 causes downward translation of lands 272, 274, 276. As aresult, pressure switch PS4 is connected with control passage 102 viapassage 231 and restrictors 161. Pressure switch PS4 is therebyactivated by control pressure. Also, valve to shift mechanism passage196 is connected with main passage 100 via passages 230 and 216 andrestrictors 150, 128. Shift mechanism fluid chamber C4 thereforereceives main pressure via restrictors 128, 150. With spool portion 336interposed in passage 338 as a result of activation of trim system PCS4,fluid in passage 338 is at the control pressure. Check valve 90 connectspassage 338 with control passage 102.

Third Forward Ratio

When the third forward ratio is requested, e.g. automatically by control22 or by range selector 24, control 16 assumes the configuration shownin FIG. 7. In the third forward ratio, PCS5 and shift valve SV1 maintainthe same position as in the first and second ratios. PCS2 is actuated,connecting PS2 with control pressure in the same manner as describedabove with reference to FIG. 2. With manual valve MV1 in the driveposition and PCS2 actuated, passage 218 is in fluid communication withvalve to shift mechanism passage 190. Thus, main pressure is applied tofluid chamber C1 through restrictor 158 to engage shift mechanism C1.Trim system PCS4 is deactuated to release shift mechanism C4.

In the third forward ratio, pressure switches PS2 and PS3 detect controlpressure. Pressure switch PS2 is in fluid communication with controlpassage 102 via shift valve SV1 and passage 232, as a result of downwardtranslation of lands 254, 256. Pressure switch PS3 remains activated bycontrol pressure as in FIG. 6.

Also, in the third forward ratio, torque converter clutch 26 is applied.Activator 40 provides control pressure to valve head 186 via passage 180and converter fluid chamber 108 is connected with main passage 100 dueto movement of land 188 to the pressure set position. The torqueconverter clutch 26 normally remains applied in the third through eighthforward ratios. The pump clutch 28 is normally applied in all ranges,unless the RELS features is activated as shown, for example, in FIG. 5.

Fourth Forward Ratio

When the fourth forward ratio is requested, e.g. automatically bycontrol 22 or by range selector 24, control 16 assumes the configurationshown in FIG. 8. In the fourth forward ratio, the position of shiftvalve SV1 and manual valve MV1 remains the same as in FIGS. 4-7, buttrim system PCS5 is deactuated. Deactuation of PCS5 causes upwardtranslation of valve 62. As a result, land 264 disconnects passage 222from main passage 100. Also, removal of C5 clutch feedback pressure frompassage 220 deactuates boost valve 80. As a result, shift mechanismfluid chambers C5 a and C5 b are exhausted and shift mechanism C5 isdisengaged. Trim system PCS4 is actuated to apply shift mechanism C4 ina similar manner as shown in FIG. 6, described above.

In the fourth forward ratio, pressure switches PS2, PS3, PS4, and PS5all detect control pressure. With PCS4 actuated and PCS3 deactuated,pressure switches PS3 and PS4 are connected with control passage 102 viapassage 231 and restrictors 161. Pressure switches PS2 and PS5 areconnected to control passage 102 via passage 232 and shift valve SV1,due to activation of PCS2 and deactivation of PCS5.

Alternative Fourth Forward Ratio

An alternative fourth forward ratio may be requested, eitherautomatically by control 22 or by range selector 24, when it is desiredto transition the transmission 18 from the first set of forward ratios1-4 to the second set of forward ratios 5-8, or for other reasons. InTable 1, the ratios denoted by “prime” are ratios in which the shiftvalve SV1 is stroked. In the illustrated embodiment, shift valve SV1 isdestroked for the lower ranges and provides a low-range limp-homecapability. Shift valve SV1 is stroked in the upper ranges and providesa higher-range limp-home capability. Note also that when shift valve SV1is stroked, shift mechanism C5 can not be applied.

In the alternative fourth forward ratio, control 16 assumes theconfiguration shown in FIG. 9. Shift valve SV1 is stroked by activationof actuator 42 applying control pressure to valve head 250. Trim valves60, 62, 64, 66 and manual valve MV1 all maintain the same position as inFIG. 8. Application of control pressure to valve head 250 shifts shiftvalve SV1 into the pressure set position. Movement of lands 278, 280,282, 284, 286 alters the connections of passages 224, 226, 228. Downwardtranslation of shift valve SV1 disconnects passage 232 and 236 fromcontrol passage 102. As a result, pressure switches PS2 and PS5 aredeactuated. Check valve 94 prevents control pressure from enteringpassage 236. Thus, in the fourth forward ratio of FIG. 8, all ofpressure switches PS2, PS3, PS4, PS5 are activated by control pressure,while in the alternative fourth forward ratio of FIG. 9, only pressureswitches PS3 and PS4 detect control pressure. This configurationprovides a positive means for detecting the position of manual valveMV1.

Fifth Forward Ratio

When the fifth forward ratio is requested, e.g. automatically by control22 or by range selector 24, control 16 assumes the configuration shownin FIG. 10. In the fifth forward ratio, trim systems PCS2, PCS3, shiftvalve SV1 and manual valve MV1 maintain the same position as in FIG. 9,engaging shift mechanism C1. Trim system PCS3 is actuated to apply shiftmechanism C3 in a similar manner to FIG. 5, described above. Trim systemPCS4 is deactivated in a similar manner to FIG. 7, described above,releasing shift mechanism C4 and deactivating pressure switch PS4. Inthe fifth forward ratio, none of the pressure switches PS2, PS3, PS4,PS5 detect control or main pressure, and are therefore not actuated.

Sixth Forward Ratio

When the sixth forward ratio is requested, e.g. automatically by control22 or by range selector 24, control 16 assumes the configuration shownin FIG. 11. PCS2, PCS5, and shift valve SV1 are actuated, maintainingengagement of shift mechanism C1 and engaging shift mechanism C2. PCS3is deactivated in a similar manner as shown in FIG. 2, described above,thereby releasing shift mechanism C3 (relative to FIG. 10). Activationof PCS5 (and thereby, boost valve 80) pressurizes lines 236 and 222.Pressure switch PS5 is thereby activated by control pressure and shiftmechanism fluid chamber C2 receives main pressure via passages 228, 192and restrictor 156. The fluid coupling arrangement of shift valve SV1and manual valve MV1 permits engagement of C2 and C1 even though theshift valve SV1 and manual valve MV1 are in the same position as in FIG.10. Also, the arrangement of fluid passages between shift valve SV1 andmanual valve MV1 permits engagement of C1 and C2 while C5 is disengaged,as shown in FIG. 11, and also permits engagement of C2 and C5 while C1is disengaged, as shown in FIG. 2.

In the sixth forward ratio, pressure switches PS3 and PS5 detect controlpressure. Pressure switch PS3 is connected to control passage 102 viapassage 231 and restrictors 161 (due to upward translation of valve 64,relative to FIG. 10). Pressure switch PS5 is connected to controlpassage 102 via passage 234 and shift valve SV1, due to downwardtranslation of valve 62.

Seventh Forward Ratio

When the seventh forward ratio is requested, e.g. automatically bycontrol 22 or by range selector 24, control 16 assumes the configurationshown in FIG. 12. In the seventh forward ratio, trim system PCS2 isdeactuated, releasing shift mechanism C1. PCS3 is actuated, engagingshift mechanism C3 as described above. The positions of trim systemsPCS5, PCS4, shift valve SV1 and manual valve MV1 remain the same as inFIG. 11.

In the seventh forward ratio, pressure switches PS2 and PS5 detectcontrol pressure. Note that in FIG. 2, pressure switch PS2 detectscontrol pressure via valve to valve passage 342, while in FIG. 12, PS2detects control pressure via valve to valve passage 238. Thus, accordingto the illustrated embodiment, pressure switch PS2 can be activated as aresult of different inter-valve passage arrangements.

In FIG. 12, valve to valve passage 238 connects pressure switch PS2 tofluid chamber 343 of valve 62, as a result of the relative positioningof valves 60 and 62 (the upward translation of land 254, in particular).Fluid chamber 343 is in fluid communication with pressure switch PS5 andalso with passage 234, which is in fluid communication with controlpassage 102 via shift valve SV1.

Eighth Forward Ratio

When the eighth forward ratio is requested, e.g. automatically bycontrol 22 or by range selector 24, control 16 assumes the configurationshown in FIG. 13. In the eighth forward ratio, trim system PCS3 isdeactuated, releasing shift mechanism C3. PCS4 is actuated, activatingpressure switch PS4 and engaging shift mechanism C4 as described above.The positions of trim systems PCS2, PCS5, shift valve SV1 and manualvalve MV1 remain the same as in FIG. 12. In the eighth forward ratio,pressure switches PS2, PS3, PS4 and PS5 detect control pressure. Whereasin FIG. 12, inter-valve passage 344 connects PS3 and PS4 to exhaust; inFIG. 13, inter-valve passage 346 connects PS3 and PS4 to controlpressure.

Failure Modes

FIGS. 14-17 illustrate configurations of control 16 in four differentfailure modes. FIG. 14 illustrates the configuration of control 16 whenthe vehicle is in reverse at the time of power failure. In thissituation, the transmission maintains the reverse mode. FIG. 15illustrates the configuration of control 16 when the vehicle is inneutral at the time of power failure. In this situation, thetransmission maintains the neutral mode after the failure. FIG. 16illustrates the configuration of control 16 when the vehicle is in oneof the first, second, third or fourth forward ratios at the time ofpower failure. In any of these situations, the transmission assumes thethird forward ratio after the power failure. FIG. 17 illustrates theconfiguration of control 16 when the vehicle is in one of the fifth,sixth, seventh or eighth forward ratios at the time of power failure. Inany of these situations, the transmission assumes the sixth forwardratio after the power failure. In this way, the arrangement of control16, including the particular configuration of fluid passages connectingto manual valve MV1, provides a number of measures, in upper and lowerratios, in the event of an electrical failure.

In the illustrated embodiment, actuators 30, 32, and 46 are normallyhigh solenoids, while the remaining actuators 34, 36, 38, 40, 42, arenormally low solenoids. As a result, in the event of a power failure,main passage 100 is able to maintain the main pressure, control passage102 is able to maintain the control pressure and trim systems PCS2, PCS5are actuated as described above.

As shown in FIG. 14, the activation of PCS2 in the power off/limp homemode for reverse allows the system to maintain the same arrangement ofcontrol 16 and transmission 18 as in the “normal” reverse mode shown inFIG. 2.

As compared to the “normal” neutral mode, the power off neutral mode ofFIG. 15 has PCS2 actuated (e.g., due to the normally high solenoid).Actuation of PCS2 causes pressure switch PS2 to detect control pressuredue to movement of land 256, which opens passage 342 to connect withPS2. Note that PS2 is activated in FIGS. 14 and 15 via inter-valvepassage 342; whereas in FIGS. 12 and 13, PS2 is activated viainter-valve passage 238.

As compared to the “normal” third forward ratio, FIG. 16 shows that thetorque converter clutch 26 is disengaged in the limp home third ratio,since actuator 40 is not actuated. Pump clutch 28 remains engagedbecause the RELS fluid chamber 202 is not required to be pressurized toengage pump clutch 28. In the embodiment of FIG. 16, there is no otherdifference in the configuration of control 16 between the normal andpower off modes for the third forward ratio.

The same arrangement of fluid passages between shift valve SV1 andmanual valve MV1 is maintained in the limp home sixth forward ratio asin the normal sixth ratio, by check valve 94. Check valve 94 allowsfluid pressure from line 236 to flow to valve head 250 in the absence ofelectrical input to activator 42. As compared to the “normal” sixthforward ratio, FIG. 17 also shows that the torque converter clutch 26 isdisengaged in the limp home sixth ratio, since actuator 40 is notactuated. Pump clutch 28 remains engaged because the RELS fluid chamber202 is not required to be pressurized to engage pump clutch 28. Table 2shows the status of components of control 16 during single and doublerange shifts, respectively. Table 2 also indicates the applied shiftmechanisms and the status of the torque converter clutch 26 duringsingle range shifts. The asterisk is used to denote that what is shownis a typical configuration; however, the torque converter clutch can beapplied at any time.

TABLE 2 SINGLE RANGE SHIFTS Torque Shift Trim Shift Trimming ConverterMechanism(s) System(s) Valve Trim Clutch Range Shift Applied ActuatedActuated? System(s) Status* Neutral 

C5 PCS5 No PCS2 Released Reverse Neutral 

C5 PCS5 No PCS3 Released 1^(st) or 2^(nd-)1^(st) Neutral 

C5 PCS5 No PCS3, PSC4 Released 2^(nd)or1^(st-)2^(nd) or 3^(rd-)2^(nd)2^(nd-)3^(rd) or 4^(th-)3^(rd) C5 PCS5 No PCS2, PCS4 Released3^(rd-)4^(th) or 5^(th-)4^(th) C1 PCS2 No PCS4, PS5 Released4^(th-)5^(th) or 6^(th-)5^(th) C1 PCS2 Yes PCS3, PCS4 Applied5^(th-)6^(th) or 7^(th-)6^(th) C1 PCS2 Yes PCS3, PCS5 Applied6^(th-)7^(th) or 8^(th-)7^(th) C2 PCS5 Yes PCS2, PCS3 Applied7^(th)-8^(th) C2 PCS5 Yes PCS3, PCS4 Applied

Control 16 accomplishes single range shifts by selectively actuating anddeactuating the appropriate trim systems and pressure switches, pursuantto Table 2 and in a similar manner as described above. For example,during a shift from third forward ratio to fourth forward ratio, PCS5 istrimmed to release shift mechanism C5 and PCS2 is activated to applyshift mechanism C1. During a shift from second forward ratio to thirdforward ratio, PCS4 is trimmed to release shift mechanism C4 and PCS5 isactuated to apply shift mechanism C5. In addition, the TCC subsystem isactuated to engage the torque converter clutch. In the illustratedembodiment, the other single range shifts operate in a like manneraccording to the values listed in Table 2.

Because of the multiplexed configuration of the trim systems, only thePCS2 and PCS5 trim systems are implicated in any of the single rangeshifts to engage shift mechanisms C1, C2, and C5, as shown by Table 2.

Table 3 shows the status of components of control 16 during double rangeshifts, or skip shifts. Table 3 also indicates the applied shiftmechanisms and the status of the torque converter clutch during the skipshifts. The asterisk is used to denote that what is shown is a typicalconfiguration; however, the torque converter clutch can be applied atany time.

TABLE 3 DOUBLE RANGE (SKIP) SHIFTS Torque Applied Actuated ShiftTrimming Converter Shift Trim Valve Trim Clutch Range Shift MechanismSystem Actuated? System(s) Status* Reverse

 1^(st) C5 PCS5 No PCS2, PCS3 Released Reverse

 2^(nd) C5 PCS5 No PCS2, PCS4 Released 1^(st)

3^(rd) C5 PCS5 No PCS2, PCS3 Released 2^(nd)

4^(th) C4 PCS4 No PCS2, PCS5 Released 3^(rd)

5^(th) C1 PCS2 No PCS3, PCS5 Released 4^(th)

6^(th) C1 PCS2 Yes PCS4, PCS5 Applied 5^(th)

7^(th) C3 PCS3 Yes PCS2, PCS5 Applied 6^(th)

8^(th) C2 PCS5 Yes PCS2, PCS4 Applied

Control 16 accomplishes double range shifts or skip shifts byselectively actuating and deactuating the appropriate trim systems andpressure switches, pursuant to Table 3 and in a similar manner asdescribed above. For example, because of the multiplexed arrangement ofthe trim systems, trim system PCS5 is implicated in the skip shifts fromreverse to first, reverse to second, and first to third; and trim systemPCS2 is implicated in the skip shifts from third to fifth and fourth tosixth forward ratio.

Other charts showing additional details of the single and double rangeshifts are provided in Long et al., U.S. Provisional Patent ApplicationSer. No. 61/045,141, filed Apr. 15, 2008, which is incorporated hereinby this reference.

As described above, one or more of pressure switches PS2, PS3, PS4, andPS5 are multiplexed to provide valve diagnostics via a single pressureswitch manifold or PSM. While each pressure switch is operably coupledto a trim system to detect the position of its associated trim valve,certain of the pressure switches are multiplexed to detect the positionof shift valve SV1 and manual valve MV1. In the illustrated embodiment,pressure switches PS2, PS3, PS4 and PS5 are used to detect the positionof trim valves 60, 64, 66, 62, respectively. Also, pressure switches PS3and PS4 are used to detect when manual valve MV1 is in the reverseposition (FIG. 2), and pressure switches PS2 and PS5 are used to detectthe position of shift valve SV1. In this way, four pressure switches aremultiplexed to detect the positions of six valves.

The present disclosure describes patentable subject matter withreference to certain illustrative embodiments. The drawings are providedto facilitate understanding of the disclosure, and may depict a limitednumber of elements for ease of explanation. Except as may be otherwisenoted in this disclosure, no limits on the scope of patentable subjectmatter are intended to be implied by the drawings. Variations,alternatives, and modifications to the illustrated embodiments may beincluded in the scope of protection available for the patentable subjectmatter.

1. An electro-hydraulic control for a vehicle transmission comprising:first and second trim valves arranged to selectively communicatepressurized fluid to first, second and third transmission shiftmechanisms of the vehicle transmission; a manual valve having aplurality of manually selectable positions, the manual valve being inselective fluid communication with the first and second trim valves andselectively fluidly coupled to at least the first and secondtransmission shift mechanisms; a shift valve in selective fluidcommunication with at least one of the first and second trim valves andwith at least the third transmission shift mechanism; and first andsecond electro-hydraulic actuators fluidly coupled to the first andsecond trim valves, respectively, at least the first electro-hydraulicactuator configured to output fluid pressure in the absence ofelectrical input.
 2. The control of claim 1, wherein the secondelectro-hydraulic actuator is configured to output fluid pressure in theabsence of electrical input.
 3. The control of claim 1, wherein thefirst trim valve has at least a stroked position and a destrokedposition, and the first trim valve is configured to assume the strokedposition in the event of an electrical failure.
 4. The control of claim4, wherein the second trim valve has at least a stroked position and adestroked position, and the second trim valve is configured to assumethe stroked position in the event of an electrical failure.
 5. Thecontrol of claim 1, wherein the first trim valve is movable among aplurality of positions and configured to maintain substantially the sameposition during normal operation and in the event of an electricalfailure.
 6. The control of claim 5, wherein the second trim valve ismovable among a plurality of positions and configured to maintainsubstantially the same position during normal operation and in the eventof an electrical failure.
 7. The control of claim 1, wherein the firsttrim valve is configured to supply fluid pressure to the firsttransmission shift mechanism to maintain, in the event of an electricalfailure, a ratio achieved during normal operation.
 8. The control ofclaim 1, wherein the first trim valve is configured to supply fluidpressure to the second transmission shift mechanism to maintain, in theevent of an electrical failure, a ratio achieved during normaloperation.
 9. The control of claim 1, wherein the second trim valve isconfigured to supply fluid pressure to the second transmission shiftmechanism to maintain, in the event of an electrical failure, a ratioachieved during normal operation.
 10. The control of claim 1, whereinthe second trim valve is configured to supply fluid pressure to thethird transmission shift mechanism to maintain, in the event of anelectrical failure, a ratio achieved during normal operation.
 11. Thecontrol of claim 1, wherein the transmission comprises a plurality offorward ratios, a reverse ratio, and a neutral ratio, and the second andthird transmission shift mechanisms are configured to be engaged inresponse to an electrical failure occurring when the transmission is inthe reverse ratio to maintain the reverse ratio during the electricalfailure.
 12. The control of claim 1, wherein the transmission comprisesa plurality of forward ratios, a reverse ratio, and a neutral ratio, andthe third transmission shift mechanism is configured to be engaged inresponse to an electrical failure occurring when the transmission is inthe neutral ratio to maintain the neutral ratio during the electricalfailure.
 13. The control of claim 1, wherein the transmission comprisesa plurality of forward ratios, a reverse ratio, and a neutral ratio, andthe first and third transmission shift mechanisms are configured to beengaged in response to an electrical failure occurring when thetransmission is in a first, second, third or fourth forward ratio tomaintain operation of the transmission in the third forward ratio duringthe electrical failure.
 14. The control of claim 1, wherein thetransmission comprises a plurality of forward ratios, a reverse ratio,and a neutral ratio, and the first and second transmission shiftmechanisms are configured to be engaged in response to an electricalfailure occurring when the transmission is in fifth, sixth, seventh, oreighth forward ratio to maintain operation of the transmission in thesixth forward ratio during the electrical failure.
 15. The control ofclaim 1, wherein the first electro-hydraulic actuator comprises anormally high solenoid.
 16. The control of claim 15, wherein the secondelectro-hydraulic actuator comprises a normally high solenoid.
 17. Thecontrol of claim 1, comprising a pressure switch fluidly coupled to thefirst trim valve and configured to be pressurized in response to thefirst trim valve moving from a destroked position to an at leastpartially stroked position during normal operation and during anelectrical failure.
 18. The control of claim 1, comprising a torqueconverter clutch control valve configured to control engagement of atorque converter clutch of the transmission, and a thirdelectro-hydraulic actuator fluidly coupled to the torque converterclutch control valve, wherein the third electro-hydraulic actuator isconfigured to output fluid to the torque converter clutch control valveat an exhaust pressure in the event of an electrical failure.
 19. Thecontrol of claim 1, comprising a check valve coupled between the secondtrim valve and the shift valve.
 20. An electro-hydraulic control for avehicle transmission comprising: first and second trim valves arrangedto selectively communicate pressurized fluid to first, second and thirdtransmission shift mechanisms of the vehicle transmission; a manualvalve having a plurality of manually selectable positions; a shift valvein selective fluid communication with at least one of the first andsecond trim valves and with at least one of the transmission shiftmechanisms; and first and second electro-hydraulic actuators fluidlycoupled to the first and second trim valves, respectively, the first andsecond electro-hydraulic actuators configured to enable operation of thetransmission in a reverse ratio, neutral ratio, third forward ratio, orsixth forward ratio in response to an electrical failure.